why did Wayne?

He had been making and selling illegal "black boxes" so that people could get unscrambled satellite/cable TV channels without paying for them. This is a federal offense (which is why the FBI were involved, but the cars all screaming onto the scene was a movie fabrication).

It was not made clear in the movie, but there is a hint. In the scene where the FBI arrives, Chris and the other farm worker, Kevin, are up in the loft of the barn looking out. Kevin says something like "I told Wayne he should leave them black boxes alone," or words to that effect.

Krakauer explains it briefly in the book. Wayne was caught in an FBI sting operation (there were others involved), and he pleaded guilty and served a 4-month prison sentence. In the movie, he is shown getting out of prison in a brief shot at the end.

In one very brief scene, Chris is sitting at a table with Wayne and says something like, "These are those free satellite TV deals," (with a smile), and Wayne replies, "Hey, you said it, not me," trying to appear unknowing. It's a form of piracy...the early '90s version of illegally downloading music/movies/tv shows.

"I must express myself." - Delia Deetz